Over break, I took a trip to Oklahoma City to clear out my Grandmother’s house. Not only did I enjoy four fast food restaurants over the week, but I also climbed one of Oklahoma City’s highest peaks. Most mountain climbers are ecotourists, respecting the environments of their destinations, and helping keep the land pure for generation after generation. However, my adventure was the antithesis of ecotourism; I was visiting a landfill, and contributing to its size an entire U-Haul truck full of garbage.
The Oklahoma City Landfill may seem like a boring tourist destination, but like ecotourism, visiting a landfill can teach you as much about the environment – or even more. To understand the environmental lessons that landfills have to offer, you must first have a basic knowledge of landfills, and understand that it is more than just a pile of trash.
Most landfills are in a wide open area away from town water sources. They include a bottom liner made of clay, high density polyethylene(HDPE), or composite liners made of both materials. Below the bottom liner is a leachate collection system made of a network of pipes, and finally, a top cover is made with a clay or polyethylene membrane and a layer of topsoil.
The bottom and top covers are designed to limit contamination from leachate, contaminated rainwater that has been in contact with the decaying garbage in the landfill. Both the bottom and the top covers include either clay, polyethylene, or both, but the location and its contents will determine the materials. Landfills that are specifically for industrial waste may be able to get away with only an HDPE liner because it is most prone to household products such as alcohol, shoe polish, and peppermint oil. Such chemicals are able to permeate (pass through) HDPE, softening the material, as well as making it brittle and prone to cracks. However, most landfills handling residential waste use composite liners because the addition of Clay to the HDPE blocks many of the chemicals that permeate through HDPE, and the HDPE provides a safety net for clay, which will crack over time. The top liner, in addition to the HDPE and clay, has a layer of topsoil. The vegetation that grows atop the soil has a similar effect to seagrass; it holds the soil firmly together with its roots the same way seagrass attaches to sand dunes. Water is less likely to seep through firm ground than it is softer ground, and the cover of the landfill is less likely to deform over time. Finally, the leachate drain pipes, which sit above the bottom cover, help divert most of the leachate into waste water treatment plants for cleaning, improving the effectiveness of the bottom cover in preventing leaks.
While leachate is the biggest threat to the local environment, methane gas released by microbial anaerobic digestion of the garbage is the biggest global environmental threat. Methane is thirty times more potent than Carbon Dioxide at trapping heat, posing a real climate change threat. Until recently, the methane could only be released from the landfill through a series of vertical release pipes – as they do in Oklahoma City. Luckily, new technologies in methane collection have allowed for more productive uses of the gas such as flaring in industrial plants for burning off unused gases or in power production. In the case of power production, the gas is piped to a plant, purified, and used to run a power generator. While greenhouse gases are still released in the process, methane capture decreases the risk of explosions on a landfill, keeping workers, the environment, and the public safer and with more power.
So the next time when you have to take an unwanted vacation to an environmental hazard, remember that there are always lessons to learn and excitement to be had in the most horrid locations you can imagine.